1. Field of the Invention
The present invention relates to lockset mechanism for a closure member openable relative to a frame member and particularly adapted for use in a swinging door subjected to a marine environment.
2. Prior Art
Marine door locksets commonly are formed of metal components which, unavoidably, are subject to humid salty sea air which promotes corrosion. For locks used infrequently, the moving parts can become frozen in one position, or the operation of the locks can become stiff, necessitating replacement or at least frequent lubrication or maintenance.
It is known, of course, that some metals are more corrosion resistant than others. Nevertheless, without prohibitive expense only a few metals can be used in forming the components of known locksets containing a large number of parts, some of which are small and/or of complicated shape. To reduce expense, the various parts have been formed from metals such as brass, which are easily cast or soft enough to be machined easily but which are quite corrodible in damp air.
For example, one known lockset used in a swinging marine door has a rectangular brass casing fitable in a mortise in an edge portion of the door. The interior of the lock casing is of complicated shape for receiving the various cams, followers, levers and other parts used to actuate movement of a dead bolt and a separate latch bolt. While the bolts are chrome plated, presumably because they are projectable from the casing directly into the sea air, such internal working parts, like the lock casing, are of brass. In time the intrusion of sea air into the interior of the casing can cause the various brass parts and the casing itself to corrode, and the chrome plating of the separate bolts can be worn off by rubbing of the bolts against the other metal parts.
Use of different metals in a marine door lockset also can cause galvanic corrosion. The humid salty sea air acts as an electrolyte between different metals in close proximity to each other with the result that the more anodic metal is gradually eaten away. Such corrosion can be a substantial problem where the lockset is used in a conventional marine door having a wooden core and a skin of aluminum alloy sheet material because aluminum is highly subject to galvanic corrosion. If a lockset casing or other parts of the lockset containing brass, bronze, nickel or chromium, for example, are in close proximity to the aluminum skin, the skin will be eaten away in the area of its proximity to the lockset parts.